KERS set to give Le Mans 24-hour endurance cars a kick

Paul Marks, senior technology correspondent

(Image: Rick Dole/Getty Images)

Hybrid car technology is coming to the Le Mans 24-hour endurance race this weekend as variants of the speed-boosting Kinetic Energy Recovery System (KERS) used in Formula 1 get their first serious workout in another type of competition. Road car makers Audi and Toyota are the first to give the tech a major-league run out at Le Mans, but both are using different KERS technologies.

KERS gives F1 cars a six-second 400 kilojoules (80 brake horsepower) boost once per lap, using kinetic energy harvested during braking to turn a motor-generator - which in turn charges a lithium battery. When the driver pushes a KERS button, the battery discharges back into the motor-generator, turning the wheels faster. Energy storage does not have to be in a battery, however: supercapacitors or a fast-spinning heavy flywheel can do the job, too.

At Le Mans, the KERS systems for the heavier, fully-enclosed touring-style cars will need more energy than F1 allows - at 500 kilojoules (but dissipated at a rate that delivers 200 brake horsepower to the wheels). Toyota has opted for a KERS design that stores energy in supercapacitors to drive the rear wheels, while Audi will use a flywheel-based technology developed by Williams Hybrid Power, a spinoff of the Williams F1 team, to drive the front wheels. Flywheels have proven too big to package for F1 cars, but the roomier Le Mans cars can cope.

(Image: Rick Dole/Getty Images)

Use of such hybrid technology is backed by race organisers like the Federation Internationale d'Automobile (FIA) because it demonstrates the "road relevance" of low carbon power sources. FIA is also developing Formula-E - an all electric race series.

The prospects for hybrid Le Mans racing are already looking good: Audi's KERS equipped R18 E-tron Quattro took pole position in its class during qualifying at Le Mans yesterday.

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